diff --git a/ChangeLog b/ChangeLog
index 9b14dfc566..327e4607e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Jun 18 23:07:19 2008  URABE Shyouhei  <shyouhei@ruby-lang.org>
+
+	* gc.c (rb_newobj): prohibit call of rb_newobj() during gc.
+	  a patch from Sylvain Joyeux in [ruby-core:12099].
+
 Wed Jun 18 21:08:14 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ruby.c (verbose_setter, opt_W_getter): fixed prototypes.
diff --git a/gc.c b/gc.c
index 20af24f82d..a888d659e3 100644
--- a/gc.c
+++ b/gc.c
@@ -714,6 +714,9 @@ rb_newobj(void)
     rb_objspace_t *objspace = &rb_objspace;
 #endif
 
+    if (during_gc)
+        rb_bug("object allocation during garbage collection phase");
+
     if (v) {
 	RBASIC(v)->flags = 0;
 	th->value_cache_ptr++;